High-dose proton therapy and tomotherapy for the treatment of sacral chordoma: a retrospective monocentric study.

Radiation therapy (RT) is used for the treatment of sacral chordoma, in combination with surgery or alone for unresected tumours, to improve local control (LC) and potentially overall survival (OS). The purpose of the present study was to evaluate efficacy and toxicity of proton therapy (PT), and/or intensity modulated radiation therapy (IMRT), particularly Tomotherapy, for sacral chordoma treatment. After a median follow-up of 46 months (range, 0-125 months), eight local relapses were observed, and seven patients developed distant metastasis (particularly bone and lung). The 2- and 5- year local relapse rates were 11.4% CI (0.65-22.2%) and 29% (10.5-47.4%), respectively. Over the follow-up period, ten patients died (24.4%). The estimated 2- and 5-year OS rates were 91.4% CI (82.5-100%) and 74.5% (59.4-93.5%), respectively. Fibrosis, RT remains essential to improve local control in sacral chordoma. The combination of proton and photon seems to improve organ at risk sparing, resulting in a decreased rate of reported late toxicities.